MGA Construction Company

Weak Cripple Walls

The Problem

Wooden stud walls are sometimes used on top of an exterior
foundation to support a house and create the crawl space (see
figure below). These are called cripple walls. These short walls
carry the weight of the house. When the house sways from side to
side in an earthquake, these walls must be braced to resist
swaying. if the cripple walls are not braced, they can collapse
and the house will fall, causing dmage to the foundation, floors,
walls, windows, and utility connections as well as the contents
of the home. It may also cause a fire from broken gas lines. It
is very expensive to repair this damage.

How to Identify It

Go under the house to see if there are any cripple walls and, if
so, whether they are braced. If you can see a cripple wall, and
there is no plywood or diagonal wood sheathing (see figure
below), the cripple walls are probably inadequately braced or
unbraced. Horizontal or vertical wood siding is not strong enough
to brace cripple walls.

What Can Be Done

Plywood panels can be nailed on the inside of the studs.

Figure - If your home has a cripple wall between the
foundation and the first floor, and it is not braced with plywood
sheathing, the house may collapse in an earthquake.